Two techniques are used for particle size analysis for a slurry: Dynamic Light Scattering (DLS) and Laser Diffraction.
| Dynamic Light Scattering | Laser Diffraction | |
| Working Principle | Particle Size–>Particle motion (free diffusion) –> Fluctuations in the intensity of scattered lightParticle motion is interpreted as free diffusion and converted to size. For these measurements, particle motion is important to the results. | particle size is determined from the measured variation in the intensity of scattered light as a function of scattering angle. Particle motion is less important since scattered intensity vs. angle is a direct function of particle size. |
| Assumption | particle is a perfect sphere | particle is a perfect sphere |
| Detectable particle size | 0.5nm to 10um | 10nm to 5000um |
| Sample size | microliter | milliliter |
| Sample concentration | less scattering is preferred; A decent rule of thumb is that if the sample concentration is described in mg/mL, then DLS is the better starting point. | if a sample is highly concentrated and requires dilution before measurement, the larger sample volume of laser diffraction is advantageous. |
| Expected Impurities | might miss big particles | laser diffraction is a better choice for analyzing samples that may contain large particle impurities that need to be sensed |
| volume based measurement (q) | ||
Reference
- Horiba
- Introduction to laser diffractin
3. A basic introduction to Dynamic Light Scattering (DLS) for particle size analysis